It's a small one, but I'll take it.
Figured out that the thread on the project bike flywheel is M28x1.0. And they do make inside-threaded pullers for that. And I got the sucker off.
Progress. Slowly, but it's coming.
By the way: according to EVERY source I can find, not only is the flywheel on this threaded differently, but it faces the opposite direction from everything I've seen for this year/model...